Having come to Canada upon hearing the fake news that his biological mother Haruko is in critical condition, high school student Kaidou Haru meets a young boy named Ren. "You have a new brother. Take care of him." So instructed by his mother, Haru is forced to spend the summer with Ren. Every day is a battle with Ren, who refuses to listen to anybody. However, as Ren grows to like Haru little by little and Haru comes to adore Ren as well, they make a certain "promise"...
Maybe it's not that he won't sleep inside,
Vielleicht geht es nicht darum,
dass er nicht drinnen schlafen will.
Tal vez no sea que no quiera dormir adentro,
Tal vez no sea que no quiera dormir dentro,
Si ça se trouve,
il dort dans le garage
Forse il problema non è
che non vuole dormire dentro,
Talvez o problema dele não seja
com o fato de dormir no quarto...